Underreamer



Feb.26,1924. 1,485,249 G. H. CRAIG Y UNDERREAMER Filed Nov. 21.11921Patented Feb. 26, 1924.

STTES 1,485,249 PATENT oFFlcE.

GROVER HARRIS CRAIG, OF HOUMA, LOUISIANA, ASSIGNOR OF ONE-HALF TO JOSEPHE. THATCHER, F HOUMA, LOUISIANA.

UNDERREAMER. z

To all whom t may concern.'

Be it known that I, GROVER H. CRAIG, a citizen of the United States, andresident of Houma, in the parish of Terrebonne and State of Louisiana,have invented certain new and useful Improvements in Underreamers, ofwhich the following is a speciication.

This invention relates to underreamers especially adapted for use inconnection with rotary drilling rigs.

An important object of this invention is to provide an underreamerhaving novel means whereby the bits of the same are automaticallyexpanded when the underreamer leaves the lower end of the casing.

A further object is to provide simple means whereby the expansible bitsof the underreamer are permitted to contract when it is desired towithdraw the underreamer.

A further object is to provide an underreamer which is simple tooperate, of highly simplified construction and cheap to manufacture.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawing forming a part of this application and inwhich like numerals are employed to designate like parts throughout thesame,

Figure 1 is a vertical sectional view through the improved reamer.

Figure 2 is an end elevation of the same,

Figure 3 is a horizontal sectional view taken on line 3 3 of Figure 1.

Figure 4 is a perspective of a bit embodied in the invention.

In the drawing, wherein for the purpose of illustration is shown apreferred embodiment of the invention, the numeral 5 designates acylindrical body, the said body having its forward portion reducedslightly and interiorly screw threaded as indicated at 6 for engagementwith a drill bit of any desiredl construction. The rear portion of thebody 5 is interiorly screw threaded as indicated at 7 for engagementwith the forward end of the drill stem by means of which an underreamermay be operated.

As illustrated in Figures 1 and 2 the body 5 is provided intermediateits ends with longitudinally extending recesses 8 which receiveunderreaming bits 9. The underreaming bits 9 have their rear por bitsApplication and November 21, 1921. serial No. 516,701.

tions provided with elongated slots 10 receiving pivot pins 11 whichyform a means for pivotally supporting the underreaming and forconnecting the bits to the body. The underreaming bits 9 are urged totheir operative position by means of leaf springs 12 having theirforward portions in engagement with the inner edges of the bits andtheir rear or upper portions secured to the bottom wall of 'the recesses8 by means of cap screws 13 or otherV suitable fastening devices. Thebits 9 of which there are three are also urged to their operativepositions by means of coiled springs 14 confined between the inner wallsof the recesses 8 and the inner sides of the leaf springs 12. It will beseen that when the underreaming bits 9 are releasedl from engagementwith the casing, the same will immediately swing to their outerpositions by reason of the tension of the springs 12 and 14.

The forward portions of the underreaming bits 9 are provided withlaterally projecting pins 16 received vin L-shaped grooves or 'slotshaving branches 17 and 18 arranged at right angles to each other. Thebranches 17 extend at right angles to the longitudinal axisY of the bodyand when the pins 16 arereceived within the branches the bits are intheir inoperative positions.

However, when the bits enter the pairs of branches 18 the bits are intheir operative positions and provide a hole large enough to receive thewell casing.

The branches 18 of the L-shaped grooves in the side walls of therecesses have their upper portions extended laterally as indicated at 20to permit of the removal or insertion of the pins 16.

In operation the underreamer is introduced into the well casing with thebits 9 in their inner or inoperative position. When the underreamer bodypasses out through the lower end of the well casing the bits 9 moveoutwardly and the laterally projecting pins 16 pass upwardly in thebranches 18 of the L-shaped grooves. It will be seen that the pins 16contact with the inner walls of the branches 18 and thereby positivelyprevent an inward movement of the expansible bits 9. When it is desiredto withdraw the underreamer, it is merely necessary to pull the stemupwardly and the engagement of the outer edges of the expansible bits 9with the lower end of the casing will force the pins downwardly into theinner branches 17 whereby the expansible bits are caused to assume theirinoperative positions. The expansible bits 9 of which there are threeare termed intermediate their ends with bends which deiine shoulders 2Owhich engage the forward end of the casing and thereby cause the entireexpansible bits to move downwardly and inwardly to their inoperativepositions.

With reference to the foregoing description taken in connection with theaccompanying drawing it will be seen that an underreamer constructed inaccordance with this invention may be readily and convenientlyintroduced into a well for the purpose of enlarging the hole formed bythe main bit at the forward end of the underreamer. The flow of water ispassed through a centrally arranged opening 22 in the body 5 and throughdiagonally extending branches 23, the said branches 23 forming a meanstor supplying the eXpa-nsible bits 9.

Having thus described the invention, what fis claimed is l. Anunderreamer comprising a body havinga longitudinally extending recess, abit freely received in said recess and having an elongated slot, a pivotpin extending through said slot and slidably and pivotally connectingthe bit to the body, and spring means to urge the bit outwardly, therebeing a pin and slot connection between the lower portion of the bit andthe body.

2. An underreamer comprising a body having a series of longitudinallyextending recesses, bits received in said recesses and having elongatedslots, pivot pins extending through said slot-s and supporting saidbits, siiirings urging said bits outwardly, the walls ot said recessesbeing formed with L- shaped grooves having branches, and pins carried bysaid bits and slidable in said branches.

3,4451 underreamer comprising abody having a series .ot longitudinallyextending recesses, bits received in said recesses and having slots,pivot pins extending` through said slots and supporting said bits,springs urging said bits outwardly, the walls of said recesses beine fo`ined with L-shaped grooves having branches, pins carried by said bitsand slidable in said branches, the upper portions of the upper branchesot said L- shaped grooves being provided with lateral extensions formingpassages for said pins.

4. An underreamer comprising a body having recesses, bits received insaid recesses and having slots, pins extending through said slots andpivotally and slidably connecting the bits to the body, lea springssecured to the inner walls of said recesses and engaging theintermediate p0rtions of said bits, coiled springs confined between theinner walls ot said recesses and the inner edges of said bits andcooperating with said lea-i.z springs in urging the bits outwardly, thewalls of said recesses being provided with L-shaped grooves havingbranches extending longitudinally of and at right angles to the axis ofthe body, and pins carried by said bits and slidable in said branches,the longitudinally extending branches of said grooves terminating inlateral passages.

GROVER HARRIS CRAIG,

